ECG ECG Pharmacology and Cardiac Medications

Question 1

Which ECG change is most commonly associated with digoxin toxicity?

Accepted Answer

Prolonged PR interval and ST scooping

Answer

Digoxin toxicity characteristically causes a prolonged PR interval and a 'scooped' or sagging ST segment depression.

Question 2

A patient taking amiodarone is most likely to show which ECG finding?

Accepted Answer

Prolonged QT interval

Answer

Amiodarone prolongs ventricular repolarization, resulting in a prolonged QT interval on the ECG.

Question 3

Which class of antiarrhythmic drugs primarily works by blocking sodium channels and may widen the QRS complex?

Accepted Answer

Class I

Answer

Class I antiarrhythmics (e.g., lidocaine, flecainide) block sodium channels, slowing depolarization and widening the QRS complex.

Question 4

A patient receiving IV adenosine for SVT would most likely show which transient ECG finding immediately after the dose?

Accepted Answer

Complete heart block or brief asystole

Answer

Adenosine transiently blocks AV node conduction, often producing a brief period of complete heart block or asystole before normal rhythm resumes.

Question 5

Hyperkalemia caused by potassium-sparing diuretics (e.g., spironolactone) would first appear on the ECG as:

Accepted Answer

Peaked, narrow T waves

Answer

The earliest ECG manifestation of hyperkalemia is tall, peaked (tented) T waves due to altered ventricular repolarization.

ECG (Electrocardiogram) Practice Test